Currently 3rd generation (3G) cellular communication systems based on Code Division Multiple Access (CDMA) technology, such as the Universal Mobile Telecommunication System (UMTS) or 4G Long Term Evolution (LTE), are being deployed in order to accommodate the needs of various users. For example, an evolved NodeB (eNB) may be deployed in order to serve many diverse user equipment (UE) having different communication requirements. Of course, quality of service for a UE is an important consideration, including meeting delay requirements and providing priority service for preferred users. In order to accommodate these different needs, it is important to efficiently handle Scheduling Requests (SR) from user equipment.
At present for LTE protocols, when a user equipment has new data in an empty queue for all of its four logical channel groups (LCG), and SR is triggered such that the UE is required to send a Scheduling Request (SR) for this new data to its serving eNB and repeat the SR at each subsequent SR opportunity up to a maximum number of SR repetitions, or until the UE receives an uplink grant for the new data from the eNB. It should be noted that there are no exact rules for what can or cannot trigger an SR. In the above example, an SR is triggered when data arrives to any of the LCG's when all of the LCG's are empty. Another typical scenario is when data arrives to an empty LCG & there is no currently pending higher priority LCG data. It should be recognized that there are other SR triggers also, any or all of which being applicable for the present invention.
At present, the SR opportunity interval has a configurable period. However, longer SR intervals are possible. In general, SR reliability is believed to be about 99%. In other words, the first SR sent by the UE most probably is received properly by the eNB, and there is really no urgent need to keep sending SRs, which wastes resources.
One solution to the problem is for the eNB to ignore the next k SRs from the UE after the first SR is received from the UE, where k is some positive integer, e.g. k=1. However, as the UE is still sending SRs, this still wastes processing power, air interface resources, and could incur some RF interference from the repeated SRs. Another solution to the problem is for the eNB to accept all SRs from the UE. However, this risks generating two or more separate uplink grants in response to the same SR trigger (e.g. new data arrival) from the UE, which wastes Physical Downlink Control Channel (PDCCH) resources.
In an additional consideration, the eNB can receive an SR from a UE without yet receiving a subsequent Buffer Status Report (BSR) from the UE. The BSR identifies the priority and delay requirements of the new data. Without this BSR information, the eNB has difficulty meeting the delay requirements of different services, while not wasting capacity over assigning resources. For example, if the eNB does not yet have the BSR information, it will not know how much data a UE wishes to transmit or its priority, and the eNB will end up over granting resources that may not be needed for low priority data, resulting in delayed communications for other UEs. This could also waste PDCCH/PUSCH (Physical Uplink Shared Channel) resources, giving overly high priority to uplink grants for low priority data.
What is needed is a technique for increasing SR efficiency without wasting resources.
Skilled artisans will appreciate that common but well-understood elements that are useful or necessary in a commercially feasible embodiment are typically not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.